linux-kernel - Re: [PATCH v5 05/12] KVM: Documentation: describe GUEST_MEMFD_FLAG_NO_DIRECT

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Message-ID: <e2620083-656b-4af1-91d5-6452eda2e4a7@redhat.com>
Date: Mon, 1 Sep 2025 16:43:22 +0200
From: David Hildenbrand <david@...hat.com>
To: "Roy, Patrick" <roypat@...zon.co.uk>
Cc: "ackerleytng@...gle.com" <ackerleytng@...gle.com>,
 "Manwaring, Derek" <derekmn@...zon.com>, "Thomson, Jack"
 <jackabt@...zon.co.uk>, "Kalyazin, Nikita" <kalyazin@...zon.co.uk>,
 "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
 "kvmarm@...ts.linux.dev" <kvmarm@...ts.linux.dev>,
 "linux-arm-kernel@...ts.infradead.org"
 <linux-arm-kernel@...ts.infradead.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "linux-mm@...ck.org" <linux-mm@...ck.org>,
 "pbonzini@...hat.com" <pbonzini@...hat.com>,
 "rppt@...nel.org" <rppt@...nel.org>, "seanjc@...gle.com"
 <seanjc@...gle.com>, "tabba@...gle.com" <tabba@...gle.com>,
 "vbabka@...e.cz" <vbabka@...e.cz>, "will@...nel.org" <will@...nel.org>,
 "Cali, Marco" <xmarcalx@...zon.co.uk>
Subject: Re: [PATCH v5 05/12] KVM: Documentation: describe
 GUEST_MEMFD_FLAG_NO_DIRECT_MAP

On 01.09.25 16:30, Roy, Patrick wrote:
> On Thu, 2025-08-28 at 11:27 +0100, David Hildenbrand wrote:
>> On 28.08.25 11:39, Roy, Patrick wrote:
>>> Signed-off-by: Patrick Roy <roypat@...zon.co.uk>
>>> ---
>>>    Documentation/virt/kvm/api.rst | 5 +++++
>>>    1 file changed, 5 insertions(+)
>>>
>>> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
>>> index c17a87a0a5ac..b52c14d58798 100644
>>> --- a/Documentation/virt/kvm/api.rst
>>> +++ b/Documentation/virt/kvm/api.rst
>>> @@ -6418,6 +6418,11 @@ When the capability KVM_CAP_GUEST_MEMFD_MMAP is supported, the 'flags' field
>>>    supports GUEST_MEMFD_FLAG_MMAP.  Setting this flag on guest_memfd creation
>>>    enables mmap() and faulting of guest_memfd memory to host userspace.
>>>
>>> +When the capability KVM_CAP_GMEM_NO_DIRECT_MAP is supported, the 'flags' field
>>> +supports GUEST_MEMFG_FLAG_NO_DIRECT_MAP. Setting this flag makes the guest_memfd
>>> +instance behave similarly to memfd_secret, and unmaps the memory backing it from
>>> +the kernel's address space after allocation.
>>> +
>>>    When the KVM MMU performs a PFN lookup to service a guest fault and the backing
>>>    guest_memfd has the GUEST_MEMFD_FLAG_MMAP set, then the fault will always be
>>>    consumed from guest_memfd, regardless of whether it is a shared or a private
>>
>> WARNING: Missing commit description - Add an appropriate one
> 
> Admittedly wasn't sure what to say that wouldn't just repeat the commit title
> or the contents. Maybe that just means this shouldn't be its own patch. Will
> squash in the previous one (same for PATCH 11/12).

Very right :)

If there is nothing to say then probably everything was already said 
(other patch), lol

> 
>> WARNING: From:/Signed-off-by: email name mismatch: 'From: "Roy, Patrick"
>> <roypat@...zon.co.uk>' != 'Signed-off-by: Patrick Roy <roypat@...zon.co.uk>'
> 
> Heh, my git config only ever uses "Patrick Roy <roypat@...zon.co.uk>". Not sure
> where "Roy, Patrick" comes from, could it be the mail server mangling things?

Good question. Does it only happen through git?

When Nikita sends through amazon.com[1] it seems to be fine.

But when he also sent through amazon.co.uk [2], it's also messed up.

I suggest contacting the amazon.co.uk admin or ... sending through 
amazon.com :)


[1] 
https://lore.kernel.org/all/cda7c46b-c474-48f4-b703-e2f988470f3b@amazon.com/T/#u
[1] 
https://lore.kernel.org/all/20250828153049.3922-1-kalyazin@amazon.com/T/#u

-- 
Cheers

David / dhildenb